In certain circumstances, it is desirable to inject medication directly into human tissue. Typically, syringes or pen injection devices are used to inject medicaments into tissue areas, such as the intramuscular tissue layer, the subcutaneous tissue layer, and the intradermal tissue layer.
The assembly and operation of a typical pen injection device, as shown in FIGS. 1 and 2, is described in U.S. Patent Application Publication No. 2006/0229562, published on Oct. 12, 2006, Now U.S. Pat. No. 7,645,264, issued Jan. 12, 2010, both of which are hereby incorporated by reference in their entirety.
Pen injection devices, such as the exemplary pen injector 100, as shown in FIG. 1, typically comprise a dose knob/button 24, an outer sleeve 13, and a cap 21. The dose knob/button 24 allows a user to set the dosage of medication to be injected. The outer sleeve 13 is gripped by the user when injecting medication. The cap 21 is used by the user to securely hold the pen injector device 100 in a shirt pocket, purse or other suitable location.
FIG. 2 is an exploded view of an exemplary drug delivery pen shown in FIG. 1. The dose knob/button 24 has a dual purpose and is used to both set the dosage of the medication to be injected and to inject the dosed medicament via the lead screw 7 and stopper 15 through the medicament cartridge 12, which is attached to the drug delivery pen through a lower housing 17. In standard drug delivery pens, the dosing and delivery mechanisms are all found within the outer sleeve 13 and are not described in greater detail here as they are understood by those knowledgeable of the prior art. The distal movement of the plunger or stopper 15 within the medicament cartridge 12 causes medication to be forced into the needle 11 of the hub 20. The medicament cartridge 12 is sealed by septum 16, which is punctured by a septum penetrating needle cannula 18 located within the hub 20. The hub 20 is preferably screwed onto the lower housing 17, although other attachment means can be used such as attaching to the cartridge. To protect a user, or anyone who handles the pen injection device 100, an outer cover 69, which attaches to the hub 20, covers the hub. An inner shield 59 covers the patient needle 11 within the outer cover 69. The inner shield 59 can be secured to the hub 20 to cover the patient needle 11 by any suitable means, such as an interference fit or a snap fit. The outer cover 69 and inner shield 59 are removed prior to use. The cap 21 fits snugly against outer sleeve 13 to allow a user to securely carry the drug delivery pen 100.
The medicament cartridge 12 is typically a glass tube sealed at one end with the septum 16 and sealed at the other end with the stopper 15. The septum 16 is pierceable by a septum penetrating cannula 18 in the hub 20, but does not move with respect to the medicament cartridge 12. The stopper 15 is axially displaceable within the medicament cartridge 12 while maintaining a fluid tight seal.
A pen needle, which includes the hub 20, needle 11, outer shield 69 and inner shield 59, is typically used for a single injection and is then disposed of. Following an injection, the used needle, or “sharps”, must be properly disposed of. Used sharps may become contaminated by body fluids and the like creating a hazard for anyone that may handle them following their use. Sharps disposal containers store the disposed sharps and prevent unintentional contact with any object disposed therein. Accordingly, a need exists for a cap for an outer cover that completely encapsulates the pen needle within a puncture resistant cover and cap after use.
Another problem is properly handling a used needle while avoiding an accidental needle stick or contamination. Pen needle outer covers are typically sealed by a foil seal that is discarded after opening the outer cover to access the hub assembly. Accordingly, a need exists for a cap that seals the outer cover both before and after using the needle.